Strictly speaking, aren't the results for "49ers -football -nfl" correct if using literal term exclusion? None of those pages have the term football or nfl. But

Strictly speaking, aren't the results for "49ers -football -nfl" correct if using literal term exclusion? None of those pages have the term football or nfl. But I see what you mean in principle, Google seems all-to-eager to use fancy NLP and knowledge graph to rewrite queries, so it would be fair if they exposed a way to exclude categories as well.